The invention is in the field of measurement of the dustiness of samples of dry flowable (DF) substances. More particularly, the invention utilizes an optical apparatus to measure light reflected from dust particles in order to quantify dustiness of dry flowable substances such as pesticide formulations.
Exemplary of the prior art in this field is the above-referenced Lorenz publication which discloses use of an optical system having a stainless steel tube of circular cross-section into which a sample is dropped for measurement of the absorption of light by the sample. A digital processor is utilized to monitor and control the process of measurement and recording thereof. The record of the sedimentation process is provided by a plotter at the end of each measurement so that the spectrum thereof can be used as fingerprint for assessing the quality of the measured substance. The record contains the date, time, sample identification number, diagram of sedimentation spectrum, the instantaneous value of the dust, and the assessment.
It is desirous to simplify the measurement apparatus both mechanically and electrically and provide a simpler, yet more versatile and reliable testing chamber, associated optics system, and supporting electronics so as to obtain: (i) more precise measurement by minimizing extraneous reflections from the inner surface of the test chamber, (ii) a simple mechanical adjustment of the apparatus when the particle sizes vary from sample to sample, (iii) quick and easy calibration of the device, (iv) reliable, less expensive control of the trap door by which the sample is dumped into the test chamber, and (v) a simple means for comparing samples which does not require complex calculations and use of a recording device.
Thus, it is an object of the instant invention to utilize reflection of light from the material being evaluated, rather than absorption of the light by the material, in order that the measurement increases directly in proportion to the material and light reflected therefrom.
Additionally, it is an object of the invention to provide for vertical adjustability of the optics portion of the device in order to obtain proper measurement of a substance according to particle size of the sample under test.
Also, it is an object of the invention to provide for simple, rapid, precise, and repeatable calibration of the photodetector in preparation for each evaluation.
Further, it is an object of the invention to simplify the overall control process by utilizing a rotary solenoid which, when energized, provides the motive force for opening the trap door of the sample cup from which the substance being evaluated is dropped into the test chamber and, when deenergized, provides a force sufficient for light-tight closing of the trap door by means of the internal spring of the rotary solenoid.
Still further, it is an object of the invention to provide an integrated output in the form of a single "characteristic number" for each sample that is tested, in order that many samples may be compared easily and rapidly without requiring complex calculations or an expensive recording device.
These and other objects of the invention will become apparent from the following disclosure.